Derivatives and Hedging Activities Derivatives in Statement of Condition (Details) - USD ($) $ in Thousands		Jun. 30, 2017		Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives		$ 14,238,841		$ 17,157,269
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		39,666		53,849
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		75,804		102,065
Derivative Asset, Netting Adjustments And Cash Collateral	[1],[3]	38,483	[2]	50,904	[4]
Derivative Liability, Netting Adjustments And Cash Collateral	[1],[3]	(69,862)	[2]	(84,191)	[4]
Derivative assets		78,149		104,753
Derivative liabilities		5,942		17,874
Derivative, Collateral, Cash Posted And Related Accrued Interest		79,634		180,169
Derivative, Collateral, Cash Received And Related Accrued Interest		25,919		45,074
Variation Margin for Daily Settled Contracts, Net		54,630		0
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives		5,537,149		5,660,420
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		31,133		37,379
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		19,832		26,610
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives		8,701,692		11,496,849
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		8,533		16,470
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		55,972		75,455
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives		5,902,265		8,199,000
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		1,148		2,135
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		54,834		64,661
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives		2,255,000		2,346,000
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		6,774		13,335
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		0		0
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] | Mortgages [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives		264,427		440,849
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		374		319
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		572		10,628
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] | Collateralized Mortgage Backed Securities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Derivatives		280,000		511,000
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		237		681
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		$ 566		$ 166

[1] Amounts represent the application of the netting requirements that allow the FHLB to settle positive and negative positions, cash collateral and related accrued interest held or placed by the FHLB with the same clearing agent and/or counterparty, and effective January 3, 2017, includes fair value adjustments on derivatives for which variation margin is characterized as a daily settled contract. Cash collateral posted and related accrued interest was (in thousands) $79,634 and $180,169 at June 30, 2017 and December 31, 2016. Cash collateral received and related accrued interest was (in thousands) $25,919 and $45,074 at June 30, 2017 and December 31, 2016. Variation margin for daily settled contracts was (in thousands) $54,630 at June 30, 2017 and $0 at December 31, 2016.

[2] Amounts represent the application of the netting requirements that allow the FHLB to settle positive and negative positions, cash collateral and related accrued interest held or placed by the FHLB with the same counterparty, and effective January 3, 2017, includes fair value adjustments on derivatives for which variation margin is characterized as a daily settled contract. Variation margin for daily settled contracts was (in thousands) $54,630 at June 30, 2017.

[3] Variation margin for daily settled contracts was (in thousands) $54,630 at June 30, 2017.

[4] Amounts represent the application of the netting requirements that allow the FHLB to settle positive and negative positions and also cash collateral and related accrued interest held or placed by the FHLB with the same counterparty.